does anyone have a solution for logging an error/critical entry to the event log in 2008 R2 when RAID has an issue? I really want to set up email alerts for when this happens. I'm using the MS builtin software RAID, not hardware RAID.

I don't have a 2008 software raid myself unfortunately, but I can only imagine that the output of list volume will indicate when a drive is offline or in a faulty state. An example output of list volume looks like this

You could then pipe the output to a file and parse it with a script, and generate an email or event log entry. You would need to run this script every X minutes, e.g. with the task scheduler.

You could use EventSentry (free version available) and its application scheduler to execute this script, and generate an event/email, but you would still have parse the output from diskpart to determine whether there is a problem or not.

Edit: The status of a failed RAID in Windows is "Failed Rd" opposed to "Healthy". As such, searching for "Failed Rd" should work. Example:

I don't have a MS software raid array system set up but can't you just query for availability? Win32_logicaldisk has an availability property and a status property. On my system it's blank but I would hope that in a raid set at least one of those would be populated with the state values listed in the table.